The Copernican
myths
Mano Singham
The real story of how the scientific and religious establishments greeted
^ e Copernican revolution is quite different from the folklore. And it^s a lot
more interesting.
Mano Stngham is director or the University Center for Innovation in Teaching and Education and adtunct associate pr
physics at Case Western Reserve University in Cleveland, Ohio.
Perhaps the most famous of all sdentiHc revolutions is
the one associated with Nicolaus Copernicus (1473-1543).
The popular version of the story goes as follows:
The ancient Greeks, although they were great
philosophers and good at mapping the motions
of stars and planets, tended to create models of
the universe that were more influenced hy philosophical, aesthetic, and religious considerations
than by observation and experiment. The idea
that Earth was the stationary center of the universe, and that the stars and planets were embedded in spheres that rotated around Earth, appealed to them because the circle and the sphere
were the most perfect geometric shapes.
In the Christian era, the model also pleased
religious people because it gave pride of place to
human beings—God's special creation. The prestige of Greek philosophers like Aristotle was so
great, and commitment to religious doctrine so
strong, that many scholars stubbornly tried to retain Ptolemaic astronomy even though increasingly complicated epicycles had to be added to
make the system work even moderately well.
So when Copernicus came along with the correct heliocentric system, his ideas were fiercely
opposed by the Roman Catholic Church because
they displaced Earth from the center, and that was
seen as both a demotion for human beings and
contrary to the teachings of Aristotle. Therefore
the Inquisition persecuted, tortured, and even
killed those who advocated Copernican ideas.
Because of the church's adherence to philosophical and religious dogma, scientific progress
was held back for a millennium, It was the later
work of Tycho Brahe (1546-1601), Johannes Kepler (1571-1630), Galileo Galilei (1564-1642), and
Isaac Newton (1642-1727) that finally led to the
acceptance of heliocentrism.
Variations on this breezy version of the Copernicus story
are common in science textbooks.' How much of the story
is true? Apart from the final sentence, not much. But it's a
good illustration of how scientific folklore can replace actual
history.
Let us start with the myth that the Copernican model
was opposed because it was a blow to human pride, dethroning Earth from its privileged position as the center of
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December 2007
Physics Today
the universe. Der\nis Danielson, in his fine article on the subject,' shows how widespread that view is by quoting the eminent geneticist Theodosius Dobzhansky. With Copernicus,
Dobzhansky contends, "Barth was dethroned from its presumed centrality and preeminence." Carl Sagan described
Copemicanism as the first of a series of "Great Demotions..,
delivered to human pride." Astronomer Martin Rees has
written, "It is over 400 years since Copernicus dethroned the
Earth from the privileged position that Ptolemy's cosmology
accorded it." And Sigmund Freud remarked that Copernicus
provoked outrage by his slight against humankind's "naive
self-love."
The squalid basement
Danielson, however, points out that in the early 16th century,
the center of the universe was not considered a desirable
place to be. "In most medieval interpretations of Aristotelian
and Ptolemaic cosmology. Earth's position at the center of
the universe was taken as evidence not of its importance
b u t . . . its grossness,"
In fact, ancient and medieval Arabic, Jewish, and Christian scholars believed that the center was the worst part of
the universe, a kind of squalid basement where all the muck
collected. One medieval writer described Earth's location as
"the excrementarj' and filthy parts of the lower world." We
humans, anotlier asserted, are "lodged here in the dirt and
filth of the world, nailed and rivetted to the worst and deadest part of the universe, in the lowest story of the house, and
most remote from the heavenly arch." In 1615 Cardinal
Robert Bellarmine, a prominent persecutor of Galileo, said
that "the Earth is very far from heaven and sits motionless at
the center of the world/'In Dante Alighieri's Vte Divine Comedy, hell itself is
placed in Earth's innermost core. Dante also speaks of hell in
ways consistent with Aristotelian dynamics—not full of
flames, which would be displaced skyward by the heavier
Earth, but as frozen and immobile.
By contrast, heaven was up, and the further up you went,
away from the center, the better it was. So Copernicus, by putting the Sun at the center and Earth in orbit around it, was
really giving its inhabitants a promotion by taking them
closer to the heavens.
When and why did the history become distorted?
Danielson doesn't pinpoint when the erroneous view gained
supremacy. But he says that trom 1650 onward one can find
some writers making this revisionist claim. By the late 18th
centur}' it had taken hold completely. Johann Wolfgang von
O 2007 American Institute of Phyelcs, 5-0031-9228-0712-030-5
Nicolau5 Copernicus (1473-1543) [Courtesy
of AIP Emilio Segre Visual Archives.)
would have to be something that took it
away from the center. And no such agent was
in evidence.
In his book The Copernican Revolution, his-
torian Thomas Kultn ptiinted out that Aristotle was clearly saying that Earth was at the
center of the universe not because it was especially important but simply because it was
massive: "It so happens that the Earth and the
Universe have the same center, for the heavenly bodies do move towards the center of the
Earth, yet only incidentally, because it has its
center at the center of the universe."^
Problems with heliocentricity
Copemicus's heliocentric model, on the other
hand, created all manner of difficulties. It required Earth to be in motion, but it did not
say what caused it to move away from the
center. If Earth was not stationary at the center but was midway in the sequence of planetary orbits around the Sun, how could you
define "up" and "down"? Why would objects fall "down" if Earth were not at the center of the universe? How could objects
thrown upward fall back to the same point if
Earth was not at rest? Earth was still believed
to be the most massive object in the universe.
So if it was not drawn to a fixed point at the
center, did that mean that the universe had
no center? Could that mean that the universe
Goethe (1749-1832), for example, wrote: "Perhaps no discovery or opinion ever produced a greater effect on the
human spirit than did the teaching of Copernicus. No sooner
was the Earth recognized as being round and self-contained,
than it was obliged to relinquish the colossal privilege of
being the center of the world." Here Goethe managed to
propagate another major distortion: the notion that before
Copernicus (and Columbus) it was not known that Earth was
a sphere.^^
Aristotle's cosmology
Even Aristotle did not believe Earth to be the center of the
universe. He thought it rather to be at the center. This fine
distinction was not driven by religious dogma or human selfimpurtance but by physics arguments: In Aristotle's cosmology the universe was finite and the heavens existed beyond
its outermost sphere. The universe had a center—defined as
the center of the large outer sphere in which the stars were
embedded — and matter was d rawn to that center. In that cosmology, "up" and "down" were well defined. "Down" was
toward the center of the universe and "up" was away from
it, toward the sphere containing the stars.
The elements were earth, air, water, and fire, and each
element had its natural affinity for a location in the universe.
As could be seen from the fact that rocks fell to the ground,
earth, being heavy, was drawn to the center. Flames leaping
upwards showed that fire, being light, was drawn towards
the heavens. The model explained many things, such as why
objects fell to the ground when released from any point and
why Earth's surface was spherical. It also explained why
Earth was motionless at the center. For it to move, there
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was infinite?
Kuhn argues that there were thus excellent reasons for
rejecting the upstart Copernicus and retaining Aristotelian
cosmology and its elaboration in Ptolemaic astronomy. Accepting Copernicus would not simply replace one astronomical model with another. It also meant that a whole class of
physics problems that had been considered solved were now
suddenly unsolved. Therefore much of the initial resistance
came from within the physics and astronomy contmunities
rather than from the church.
In fact, awareness of Copemicus's work was at first
largely restricted to the community of astronomers. Only
they were interested in improving the calculation of planetary motions. Copernicus was widely respected as one of Europe's leading astronomers, and reports about his work, including his heliocentric hypothesis, had been circulating
since 1515. So when his Df RcvoluHonibu? Orbium Coelcslium
(On the Revolutions of the Celestial Spheres) was published
28 years later, it was hardly a surprise to other astronomers.
They accepted it as the most comprehensive account of celestial motions since Ptolemy.
But most astronomers also felt that the Ptolemaic system,
although complicated, could ultimately he made to work. So
while they hailed Copemicus's work and used his tables and
methods, they were skeptical of his central idea of a moving
Earth. They dismissed it as an ad hoc trick (much as Max
Planck's quantum hypothesis was initially viewed centuries
later) that turned out to be a useful tool for calculations. Tlie
idea that the motion described by some artificial model was
a convenient fiction was not unprecedented. Ptolemy himself
had said that not all of his epicycles had to be considered
December 2007
Physics Today
49
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COPERNICI TOR I N E N S I S DC R b V O L V T I O N I *
Frontispiece of a 1566 edition of Copernicus's De Revolutionibus Orbium Coeiestium, published in Basil, Switzerland. The
work was first published o few months before the author's
death in 1543.
bus orbium codcftium,
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bus tafdtm moHit ati qitodun ttmpns M h
tnuum Itudior f
UK porcrit.
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physically real. Some were to be thought of as merely mathematical devices that gave sound results.
Initially, however, the Copernican system did not give
better numerical rosults than the I'tolemaic. Part of the problem was that some of the existing astronomical observations
were simply erroneous, a problem that plagued Ptolemaic
and Copemican astronomy alike. Although better observations soon eliminated some ot^ those problems, other problems remained obdurate for a long time. Furthermore, at the
level of accuracy available to Copernicus, the introduction of
ellipses in place of circular orbits would not have helped.
What Copernicus needed to do, as historian Owen Gingerich
puts it, was to "treat Earth and MercT.iry the same way as the
other planets."
Kuhn says of Copernicus: "His full system was little if
any less cumbersome than Ptolemy's had been. Both employed over thirty circles; there was little to choose between
them in economy. Nor could the two systems be distinguished by their acairacy. When Copernicus had finished
adding circles, his cumbersome sun-centered system gave results as accurate as Ptolemy's, but did not give more accurate
results. Copernicus had failed to solve the problem of the
plnnots.'"'
Johannes Kepler (1571-1630) at age 39. (Courtesy of the
Kremsmunster Observatory.)
liocentrism was eventually accepted. As Kulin puts it, "De
Rei'olutionibus did convince a few of Copemiais' successors
that sun-centered astronomy held the key to the problem of
the planets, and these men finally provided the simple and
accurate solution that Copernicus had sought.'"^
That's an important point about scientific revolutions. At
the start, the new theory rarely gives convincingly better results than its predecessor. What usually happens is that it has
some appeal, often aesthetic, that attracts others to work
within the new model. And if, over time, the new model
proves fruitful in resolving many puzzles, it gains adherents."
The success of the Copernican model was aided by the
work of the Danish astronomer Tycho Brahe, who died a few
Advantages
years before the invention of the telescope. Tycho is considThe Copernican model did have some aesthetic and qualita- ered the greatest of the naked-eye observers. His widetive advantages. It provided a more natural qualitative ex- ranging and accurate observations had an em>rmous impact.
planation for the zigzag motion of planets like Mars as obAlthough Tycho's pivotal role is recognized, what is It'ss
served from Earth, and it answered some important well known is that he, like most astronomers at the time, requestions about the ordering of the planets. That's why he- jected Copernicus's ideas of a moving Earth. It created more
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December 2007
Physics Today
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Galileo Galilei (1564-1642) as drav/n by
Ottavio Leoni around 1624.
cumbersome epicycles. But his accurate Rudolyhinc
Tables for planetary motion, published in 1627, were
difficult to use. It was Newton's theories of motion
and gravity, not published until 60 years later, that
sealed the scientific case in favor of Copernicus by
putting his model on a firm theoretical footing.
Religious objections
problems, he thought, than it solved. But despite Tycho's opposition, his observations provided two major benefits for the
heliocentric model: They got rid of some erroneous old data
that had plagued all the earlier models and thus helped to remove some of the anomalies that the Copernican system
couldn't explain. More important, the precision of Tycho's
data provided puzzles that enabled Kepler, a convert to
Copemicanism, to come up with the key idea that the motions of the planets were not circular—as Ptolemy, Copernicus, and Tycho had all assumed— but elliptical.
In the folklore that surrounds Copernicus, the introduction of elliptical orbits is rightly recognized as a crucial development that led to ultimate acceptance of his model. The
pre-Keplerian astronomers, however, are unfairly characterized as insisting on circular motion because of aesthetic considerations, slavish adherence to the authority of the Greeks,
and so forth. But at the time, the reasons for assuming circular motions were quite sensible. Because there were no good
theories of force or gravity, one needed to have an explanation of motion. Circular motion could be explained by a plausible hand-waving argument. One could say that it was an
initial condition —that once an object had been set in circular
motion it would, if undisturbed, continue circling forever.
More complicated motions like elliptical orbits would
mean that the planets' speeds and distances from the Sun
were constantly changing. But that required a dynamical theory that simply did not exist in those pre-Newtonian times.
Just introducing the idea of a moving Earth created all kinds
of unsolved problems for the physical theories of the day.
Adding noncircular motion would have compounded those
problems, providing even stronger grounds for rejecting
Copernicus.
Kepler's innovative idea of elliptical orbits, coupled with
his law of areas, did let the Copernican model dispense with
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riie actual religious reaction to the heliocentric model
also differs from the folklore. For one thing, Copemicus did not seem to fear religious opposition to his
ideas. After all, he was a reputable cleric himself. He
even dedicated his bixik to Pope Paul 111 witli a letter
in which he apologized for the seeming outlandishness of his suggestion that the Earth moved. He explained that he was forced to tliat hypothesis by the
inadequacy of the Ptolemaic .system for constructing
calendars and predicting the positions of stars. A cardinal and a bishop were among those who urged him
to publish his book. In fact, for 60 years after Copernicus's death just two months after its publication, Dc
Revoiutionihm was read and at least partially taught
at leading Catholic universities.
In 1600 the church did bum at the stake the
philosopher Giordano Bruno, an adherent of Copernicus, for heresy. But Bnmo was condemned for
other heresies against Christian doctrine rather than
explicitly for being a (Topernican. However, the fact that
Bruno had been an advocate and popularizer of heliocentrism may have led to the later perception that he was the first
martyr of the new science.
For many years after the publication of De RevohtHonibus,
while Copernicus's ideas remained within the mathematical
astronomy community, authors of more popular books on astronomy and cosmology were either unaware of his work or
chose to ignore it. A few nonastronomers did ridicule it—not
for being heretical but for promulgating the patently absurd
idea of a moving Earth.
It was through popularizers, some of them poets, that
Copemicus's ideas eventually became more widely known and
began to spark religious opposition. But here too, Uie actual history is surprising. Opposition arose initially among Protestant
groups rather than from the Roman Catliolic Church.
Kuhn suggests that this was because Martin Luther
(1483-1546) and other leaders of the Reformation were emphasizing the Bible as the fundamental source of Christian
knowledge and authority. And there were manifest contradictions between the Bible and Copemicus. The Catholic
Church, by focusing more on doctrinal issues, actually had
greater flexibility in dealing with science.
Luther spoke out against heliocentrism in 1539, saying
that the idea of a moving Earth going around a stationary Sun
clearly went against the account in the book of Joshua that
says Joshua commanded the Sun to stand still. Luther's
deputy Philipp Melanchthon followed up by finding other
biblical verses that described Earth as stationary.
The conflict between scripture and Copemicanism was
not limited to verses that involved the motion of Sun or Earth.
The realization was growing that acceptance of Copemicanism raised other profound theological difficulties as well. As
Kuhn points out, the problems just kept multiplying:
December 2007
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51
When it was taken seriously, Copernicus' proposal raised many gigantic
problems for the believing
Christian. If, for example,
the Earth were merely one
of six planets, how were
the stories of the Fall and
of the Salvation, with their
immense bearing on
Christian life, to be preserved? If there were other
bodies essentially like the
Earth, God's goodness
would surely necessitate
that they, too, be inhabited.
But if there were men on
other planets, how could
they be descendants of
Adam and Eve, and how
could they have inherited
the original sin? . . . Again,
how could men on other
planets know of the Savior
who opened to them the
possibility of eternal life?
Or, if the Earth is a planet
and therefore a celestial
body located away from
the center of the universe,
what becomes of man's intermediate but focal position between the devils
and the angels? If the Earth, as a planet, participates in the nature of celestial bodies, it cannot
be a sink of iniquity from which man will long to
escape to the divine purity of the heavens. Nor
can the heavens be a suitable abode for God if
they participate in the evils and imperfections so
clearly visible on a planetary Earth. Worst of all,
if the universe is infinite, as many of the later
Copemicans thought, where can God's Throne
be located? In an infinite universe, how is man to
find God or God man?''
As time went on, Copemicus's Ideas were seen as seriously disturbing to Christianity; they had to be countered.
Soon the Bible became the main weapon used against Copernicus. Protestant and Catholic derics in the 17th century
started combing through it for ammunition. People started
calling the Copemicans infidels and atheists and urged their
repression. But the new Protestant churches did not have the
powers of suppression and enforcement that the longestablished Catholic Church had.
Kuhn argues that it was probably the menace of burgeoning Protestantism that caused the Catholic hierarchy in
1616 to switch abruptly from tolerance of Copernicanism to
repression. "Copemican doctrines were, in fact, condemned
during the Counter Reformation, just when the Oiurch was
most convulsed by internal reforms designed to meet Protestant criticism. Anti-Copernicanism seems, at least in part, one
of these reforms. Another cause of the Church's increased
sensitivity to Copernicanism after 1610 [the year Galileo first
turned a telescope to the heavens] may well have been a delayed awakening to the fuller theological implications of the
Earth's motions. In the I6th century those implications had
rarely been made explicit.'"'
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December 2007
Physics Today
Giordano Bruno, burned at the stalce as a heretic in
1600, was honored in 1 887 with the erection of this
statue at the site of his execution in Rome's Campo
dei Flori. Although Bruno was condemned by the Inquisition primarily br theological heresies rather
than for his advocacy of heliocentrism, he is
widely regarded as the first martyr of the scientific revolution.
The ide.i ot the Copernican
model being a demotion for humanity probably first developed
around 1650, after tlie scientific
community had already accepted
heliocentrism. Religious bodies undertook what was essentially a
propaganda war against Copeniicus. What probably happened was
that after the heliocentric model had
been well established, the liKation of
the Sun did come to be perceived as
a privileged place. So people read
back into history the newly believed
excellence of the center and attributed that belief retrospectively to the
pre-Copernicans. The demotion
idea may have been introduced as
part of the effort to rally nonscientific religious people to tum against
Copernicanism by appealing to
their pride as human beings.
The Protestant churches abandoned their opposition to Copemicanism fairly quickly when
it became clear that the evidence in favor of a Sun-centered
system was overwhelming. But the Catholic Church, being a
much larger and more tradition-bound and bureaucratic institution, was left clinging to its anti-Copemican views for a
long time. Its ban on Copernicus remained until 1822, and his
book remained on the forbidden list until 1835. In fact it was
only in 1992 that Pope John Paul II lifted the edict of inquisition against Galileo. Thus the Roman Catholic Church is now
generally regarded as the principal villain in perhaps the
most notorious episode in the history of science.
What can we learn from all this? The story of the Copernican revolution shows that the actual history of science often
bears little resemblance to the popular capsule versions that
are learned in school or college or portrayed in textbooks and
the popular media. Steven Weinberg calls them "potted history." TTie true story is much more complicated, but it's also
a tot more interesting.
My thanks to Ouvn Gingerich for an enlightening discussion and
many helpful suggestions.
References
L See, for example, P. Fishbane, S. Ga.siorowia!;, S. Thomton, PJri/s/cs
for Scientists and Engineers, 2nd ed., I'rentice Hdll, Upper Saddle
River, NJ (19%), pp^ 1, 320, 321.
2. D. R. Danieison, Airi.}. Phys. 69, 1029 (2001).
3- M. Singham, Phi Delta Kapyan 88, 590 (2007).
4. J. B. Russell, hiventing the Flat Earth: CDlumhu^ and Modem Historians, Praeger, New York (1991).
5. T Kuhn, TIte Copernican Rei>clulioii: Phinctary Aatrononiy in the
De^vlopment of Western Thought, Harvard U, Press, Cambridge,
MA (1957).
6. I. Lakatos, The Methodology of Scientific Research Programmes, Cambridge U. Press, New York (1978).
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